Known service switching devices can be, for example, line circuit breakers, motor circuit breakers or residual current circuit breakers, whose connection terminal arrangement can be designed specifically for connecting a connecting conductor with a so-called annular terminal lug, for example with a terminal lug with a closed ring. A hole can be located in the annular terminal lug, wherein the clamping screw is guided through the hole during clamping.
DE 10 2007 039 709 A1 discloses a service switching device in which a thread element, with which a screw shaft can be engaged, is in the form of a threaded bore in a connecting plate. The clamping screw is screwed directly to the connecting plate. In this case, the connecting plate is provided with a corresponding thickness and stability in order for it to be able to absorb even a relatively large clamping torque when the clamping screw is tightened without being distorted or without the thread breaking. This can involve relatively high material costs and relatively complex manufacture.
DE 695 16 034 T2 discloses a service switching device, in which a thread element is in the form of a nut, which is held in a nut accommodating cutout in a housing. The clamping screw is screwed to an additional part, a nut, and not directly to a connecting plate. Nevertheless, the nut applies the entire force to housing parts in which the nut is mounted in locking fashion when the clamping screw is tightened. This can result in excessive loading on the housing and in distortion or even breakage of housing parts.